Cauliflower Casserole

Got this from an online source (don't remember where). Great winter dish!

• Ready In: 45 mins
• Serves: 4

Ingredients

• 1  head cauliflower (about 2 pounds)
• 3  cups penne pasta
• 5  tablespoons unsalted butter, divided
• 1⁄4 cup all-purpose flour
• 3  cups milk, heated
• 2  cups swiss cheese, shredded
•  salt & freshly ground black pepper
• 1⁄4 cup parmesan cheese, parmesan cheese
• 1  tablespoon  dried breadcrumbs

Directions

1. Position a rack in the center of the oven and preheat the oven to 350 degrees F. Lightly coat the inside of a 2- to 3-quart baking dish with the oil spray.
2. Bring a large pot of lightly salted water to a boil over high heat. Add the cauliflower and return to a boil. Cook just until the cauliflower is barely tender, about 3 minutes (it will cook further during baking, so do not overcook). Using a scoop or a large slotted spoon, transfer the cauliflower to a large bowl of very cold water to cool. Drain well.
3. Add the penne to the same pot of boiling water and cook just until barely tender (it will cook more in the oven), about 7 minutes. Drain well.
4. Meanwhile, melt 4 tablespoons butter in a medium heavy-bottomed saucepan over medium-low heat. Whisk in the flour and let the mixture bubble without browning for 2 minutes. Whisk in the hot milk and bring to a boil over medium heat, whisking often. Return the heat to medium-low and let the sauce simmer until it is slightly thickened and has no raw flour taste, about 5 minutes. Stir in the Gruyere cheese. Season with salt and pepper. Transfer to the baking dish. Mix the Parmesan cheese and bread crumbs, sprinkle over the pasta, and dot with the remaining 1 tablespoon butter.
5. Bake until the sauce is bubbling and the topping is golden brown, about 30 minutes. Let stand for 5 minutes, then serve hot.